1. Field of the Invention
The invention is directed to industrial manipulators. More particularly, the invention is a compliance system which provides a range of compliant control. Additionally, the invention includes a system for directly and accurately measuring radial and axial deflections in the compliance system in order to provide positional information.
2. Description of the Prior Art
It is an objective in the design and construction of industrial manipulators to mimic limited aspects of various human capabilities in order to improve the positional accuracy of industrial manipulators in such tasks as the mating between two parts, a tool and a part, a part and a fixture, and many other mating pairs. When parts are of an exact nature and the tools and jigs holding them are precisely located, there are no errors in assembly. However, not all surfaces on a part are held to the same tolerance and often the mating surfaces are not in perfectly known positions. The design and construction of mechanical manipulators ultimately involves a compromise between manipulator speed, payload capacity and positional accuracy in order to cope with aforedescribed imperfections.
It has been known to utilize a compliant device as an aid in overcoming the imperfections encountered in mating operations. The compliant device addresses these difficulties by functioning as a multi-axis "float" which accommodates positional and angular misalignments between parts. U.S. Pat. No. 4,098,001 discloses a remote center compliance device which holds a workpiece so that the workpiece can rotate about the point where it engages a mating part. Lateral error and angular error are absorbed independently so that the workpiece is responsive to contact forces during insertion, and realignment with the insertion axis is passively accommodated.
It has also been suggested that sensory feedback utilizing vision or tactile devices be employed to facilitate the positional accuracy requirements of industrial manipulators. To this end, force sensing apparatus, which involve strain analysis, have been incorporated into compliance devices. An example of a force sensing apparatus capable of six degrees of freedom is disclosed in U.S. Pat. No. 4,094,192. However, in industrial applications, the response to the force sensor apparatus by large manipulators is usually not fast enough to prevent large forces from occurring. Therefore, a degree of mechanical compliance is added to make the manipulator system more forgiving.
It is an object of this invention to provide an adjustable compliance which is capable of a range of compliant control.
It is also an object of this invention to provide a compliance system with five and one-half degrees of freedom.
It is yet another object of this invention to produce positional feedback information.
It is yet another object of this invention to provide a compliant device which is capable of a variety of applications requiring a significant range of strength and precision.